JP2010008789A - Optical member, optical system having the same, and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member capable of preventing color difference caused by a change of an incident angle of light, to provide an optical system having the same member, and to provide an optical device with the optical system. <P>SOLUTION: In the optical member used at ≥30° incident angle of visible light, the optical member has 2 to 4 maximum values in a spectral characteristics of the visible light and when the incident angle of light in the optical member is changed, a variation width of the spectral characteristics of the optical member in the vicinity of peak wavelengths λx, λy and λz to be products of the spectral characteristics of the visible light of a used light source and CIE three stimulus values x, y and z is formed to be within 20%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical member, an optical system having the optical member, and an optical apparatus.

In an optical system that observes with the naked eye, it is important that the color difference between the object being observed or the resulting image and the object is small, but the incident angle of light incident on the optical components inside the optical system changes. It is known that a color difference occurs (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-228057

  Conventional optical components have not been able to cope with suppressing the color difference caused by the change in the incident angle of the incident light beam.

  In order to solve the above problems, the present invention is an optical member that is used at an incident angle of visible light rays of 30 degrees or more, and the optical member has a maximum value of 2 to 4 in the spectral characteristics of the visible light. And when the incident angle of the light beam to the optical member changes, the product of the spectral characteristic of the visible light of the light source used and the CIE tristimulus values x, y, z is near the peak wavelengths λx, λy, λz. The optical member is characterized in that the fluctuation range of the spectral characteristics of the optical member is formed within 20%.

  The present invention also provides an optical system having the optical member in an optical path.

  Moreover, this invention provides the optical apparatus characterized by having the said optical system.

  ADVANTAGE OF THE INVENTION According to this invention, the optical member which can suppress the color difference resulting from the change of the incident angle of a light ray, an optical system and an optical apparatus which have this can be provided.

  Hereinafter, an optical member according to an embodiment of the present invention will be described with reference to the drawings. The following embodiments are merely for facilitating understanding of the invention, and excluding additions and substitutions that can be performed by those skilled in the art without departing from the technical idea of the present invention. It is not intended.

Figure 1 shows the spectral characteristics of the stimulus value obtained by multiplying the illuminant D ₆₅ characteristics and CIE3 stimulus value. FIG. 2 shows spectral reflectance characteristics of the optical member according to the embodiment. FIG. 3 shows the light incident angle and the CIE color coordinate value on the optical member according to the embodiment. FIG. 4 is a schematic configuration diagram of a camera having an optical member according to the embodiment.

  First, a color difference correction method in the naked eye observation will be briefly described. The color system in the naked eye is, as shown in the CIE (International Commission on Illumination) standard, in the wavelength range from 380 nm to 780 nm, which is visible light, and the spectral characteristics and tristimulus values x, y, z of the light source used. The color is perceived by the spectral characteristics (spectral reflectance, spectral transmittance, etc.) of the object. Further, if the change in the spectral characteristics in the vicinity of the wavelengths λx, λy, and λz indicating the peak value is small in the stimulation value obtained by multiplying the spectral characteristics of the light source and the tristimulus values x, y, and z, the spectral characteristics of other wavelengths It has been found that the color visible to the naked eye doesn't change even if changes greatly. In the following description, spectral reflectance is described as a representative spectral characteristic, but it goes without saying that the same effect can be obtained with spectral transmittance.

  The optical member according to the embodiment is used at a light incident angle of 30 degrees or more, and has a maximum value of 2 to 4 in the spectral reflectance characteristics of visible light having a wavelength of 380 nm to 780 nm. When the incident angle of the light beam changes, the fluctuation range of the spectral reflectance characteristics in the vicinity of the peak wavelengths λx, λy, λz of the product of the spectral characteristics of the light source used and the CIE tristimulus values x, y, z is within 20% It is formed to become.

  By forming the optical member in this manner, the spectral reflectance change in the vicinity of the peak value wavelengths λx, λy, and λz is suppressed to a predetermined range, and it occurs when the incident angle of the light incident on the optical member changes. It makes it possible not to feel the color difference.

Figure 1 shows the spectral reflectance characteristics of the stimulus value obtained by multiplying the illuminant D ₆₅ characteristics and CIE3 stimulus value. From this figure, the wavelengths at which the stimulation value peaks are approximately λx = 600 nm, λy = 550 nm, and λz = 450 nm. If the optical thin film is formed so that the fluctuation range of the spectral reflectance characteristics of the optical member falls within a predetermined range when the incident angle of the light beam changes in the vicinity of these wavelengths, the color difference should not be felt with the naked eye. Is possible.

  FIG. 2 shows spectral reflectance characteristics of, for example, a half mirror formed by an optical thin film designed based on the above guidelines. Hereinafter, a half mirror will be described as a representative optical member.

  As can be seen from FIG. 2, the half mirror according to the embodiment has two maximum values (incident angles of 45 and 35 degrees) or three (incident angles of 55 degrees) in the spectral reflectance characteristics of visible light. Yes. In FIG. 2, in the case of the incident angle 35, the reflectance is 71.63% when the wavelength is 450 nm, and the reflectance is 71.81% when the wavelength is 598 nm.

  Thus, in the spectral reflectance characteristic, a small maximum value corresponds to a small number of optical thin films such as an antireflection film formed on the half mirror. Thereby, the manufacturing man-hour of an optical member can be reduced and a half mirror can be manufactured cheaply.

  Further, as shown in FIG. 2, when the peak wavelength λx = 600 ± 30 nm, λy = 550 ± 30 nm, λz = 450 ± 15 nm, and the incident angle θi of the light beam is 45 degrees ± 10 degrees, the reflectance fluctuation range is 20 %.

  For example, the peak wavelength λx has a reflectance of 70.86% (θi = 35 °), 71.91% (θi = 45 °), 72.61% (θi = 55 °) at a wavelength of 570 nm, and a reflectance at a wavelength of 600 nm. 71.81% (θi = 35 °), 71.57% (θi = 45 °), 69.94% (θi = 55 °), reflectivity 69.76% (θ = 35 °) at a wavelength of 630 nm, 67 .17% (θi = 45 °), 62.41% (θi = 55 °).

  The peak wavelength λy is 67.60% (θi = 35 °), 68.23% (θi = 45 °), 69.46% (θi = 55 °) at a wavelength of 520 nm, and the reflectance is 69.60% at a wavelength of 550 nm. 63% (θi = 35 °), 70.91% (θi = 45 °), 72.38% (θi = 55 °), reflectance 71.41% (θ = 35 °) at a wavelength of 580 nm, 72.16 % (Θi = 45 °) and 72.23% (θi = 55 °).

  The peak wavelength λz is 67.89% (θi = 35 °), 69.84% (θi = 45 °), 69.12% (θi = 55 °) at a wavelength of 435 nm, and the reflectance is 71.71 at a wavelength of 450 nm. 63% (θi = 35 °), 70.13% (θi = 45 °), 69.25% (θi = 55 °), reflectance at a wavelength of 465 nm, 70.44% (θ = 35 °), 68.71 % (Θi = 45 °) and 68.67% (θi = 55 °).

  FIG. 3 is a table showing incident angles of light rays to the half mirror and CIE color coordinates X and Y. At each incident angle, X is about 3.110 and Y is about 3.320, and the variation of the color coordinates is small. As a result, even if the incident angle of the light beam changes, the half mirror does not feel a color change with the naked eye.

Thus, in the half mirror according to the _{embodiment, D 65} light source characteristics and CIE3 stimulus values x, y, a peak wavelength [lambda] x ± 30 nm of the stimulus value when multiplied by the z, [lambda] y ± 30 nm, the reflection of the [lambda] z ± 15 nm By suppressing the fluctuation range of the rate within 20%, it is possible to prevent the color difference from being felt with the naked eye. In order to secure the effect of the embodiment, it is preferable that the fluctuation range is within 15%. In order to further secure the effect of the embodiment, it is preferable that the fluctuation range is within 12%.

In addition, this half mirror achieves the above characteristics with an optical thin film (TiO ₂ / SiO ₂ ) of 10 layers or less. This reduces the color difference when the incident angle of the light beam is changed with a small number of layers compared to the case where an optical thin film of 12 to 15 layers or more is formed in order to make the visible light reflectance characteristic substantially flat. Have achieved that.

  Next, a camera having an optical member according to the embodiment will be described with reference to FIG.

  In FIG. 4, the camera 1 is a digital single-lens reflex camera provided with a photographing lens 2. In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and focused on the focusing screen 4 through the quick return mirror 3 that is an optical member according to the embodiment. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image with the eyepiece 6.

  When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. As a result, light from the subject is picked up by the image sensor 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  By having the quick return mirror 3 of the optical member according to the embodiment, the camera 1 can achieve high imaging performance with no color difference even when the incident angle of the light beam changes.

As described above, the optical member according to the embodiment, the light source used (e.g., D ₆₅ light source) of the spectral characteristics and CIE3 stimulus values x, y, peak wavelength λx stimulus value obtained by multiplying the z, [lambda] y, By making the fluctuation range of the spectral reflectance near λz within a predetermined value, the color difference with the naked eye is reduced. As a result, the number of layers of the optical thin film can be reduced as compared with the prior art, and the optical member can be manufactured at low cost.

  The spectral characteristics in the embodiments are not limited to mirrors such as half mirrors and quick return mirrors, but can be applied to other optical members such as lens surfaces or filter surfaces.

In the above description, the D ₆₅ light source is described as an example of the light source. However, other light sources (for example, standard light source A, auxiliary standard light source C, etc.) or light sources actually used (for example, mercury lamp, xenon lamp, Needless to say, the same effect can be obtained with an auxiliary light source of a camera.

  Moreover, although the camera was shown as an optical apparatus, it cannot be overemphasized that it is applicable also to optical measuring instruments other than this.

Multiplied by the illuminant D ₆₅ characteristics and CIE3 stimulus value shows the spectral characteristics of the stimulus value. The spectral reflectance characteristic of the optical member which concerns on embodiment is shown. The incident angle of light on the optical member according to the embodiment and the CIE color coordinates X and Y are shown. The schematic block diagram of the camera which has the optical member (quick return mirror) which concerns on embodiment is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera 2 Shooting lens 3 Quick return mirror 4 Focusing plate 5 Penta prism 6 Eyepiece 7 Imaging element

Claims (7)

An optical member used at an incident angle of visible light rays of 30 degrees or more,
The optical member has a maximum value of 2 to 4 in the spectral characteristic of the visible light, and when the incident angle of the light beam to the optical member changes, the spectral characteristic of the visible light and the CIE tristimulus value of the light source to be used An optical member characterized in that the fluctuation range of the spectral characteristics of the optical member in the vicinity of the peak wavelengths λx, λy, λz of the product of x, y, z is formed within 20%.   2. The optical member according to claim 1, wherein the fluctuation range satisfies the peak wavelengths λx, λy, and λz in a range of λx ± 30 nm, λy ± 30 nm, and λz ± 15 nm.   The said optical member has an optical thin film of 10 layers or less, The optical member of Claim 1 or 2 characterized by the above-mentioned.   The optical member according to claim 1, wherein the optical member includes a mirror.   The optical member according to claim 1, wherein the optical member has refractive power.   6. An optical system comprising the optical member according to claim 1 in an optical path.   An optical apparatus comprising the optical system according to claim 6.

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